Macbook pro slow at login screen after initial boot

[rrrrr]

I have recently bought a 2015 macbook pro running el capitan.

The laptop boots to the login screen very fast, but once it is at the login screen, it is very laggy when trying to enter password. Can take a few minutes to be able to enter a complete password. ( lags after every few characters, causing me to miss type password).

Once i have entered password in correct, login times are fast and there is no lag during normal use.

 

Also, returning to login screen from sleep is also fine.

 

Becoming a pain when starting laptop, just keeping in sleep mode now due to this.

 

Any ideas?